The present invention is directed to a method for diagnosing the subluxation of a skeletal articulation which may be an appendicular joint or an intervertebral joint of the spinal column.
It has been reported that 60% to 80% of the general population will experience at least one episode of low back pain (LBP). Fischgrund, J. S., and Montgomery, D. M., "Diagnosis and Treatment of Discogenic Low Back Pain," Orthopaedic Review, 22(3), pp. 311-318 (March 1993) [1]. Indeed, at any given time, more than 10% of the population is reported to suffer some degree of LBP. Katz, J. N. "The Assessment and Management of Low Back Pain: A Critical Review." Arthritis Care and Research, 6(2), pp. 104-14 (June 1993) [2]. The direct medical costs associated with the treatment of LBP in 1990 were estimated to have exceeded $23 billion in the United States alone[2]. Indirect costs, including the lost wages of injured workers, the lost earnings of spouses who cared for injured spouses, and production losses to employers, additionally range from between $10 and $20 billion annually [2].
The diagnosis and treatment of LBP may be analogized to an engineering problem. In structure, as described by Gray, "Anatomy, Descriptive and Surgical," Bounty Books, N.Y. (1997) [3], and by Williams, P. L., Warick, R., Dyson, M., and Bannister, L. H., "Gray's Anatomy," 37th ed., Churchill Livingstone, Edinburgh (1989) [4], the spine is a flexible column of bone formed from the junction of the vertebrae. The vertebrae generally are thirty-three in number, and are designated according to position along the column as seven cervical (C1-7), twelve thoracic (T1-12), five lumbar (L1-L5), five sacral (S1-S5), and four coccygeal (Co1-Co4). According to the general vertebrate plan, the spine is situated dorsally in the median line of the human body. Viewed anteriorly, the spine presents two pyramidal regions, an upper formed of the vertebrae from C2 through L5, and a lower formed of the sacrum and the coccyx. The upper region increases in mass and width from an apex at the first cervical vertebra or atlas through L5, which increase is indicative of a corresponding increase in load bearing capacity. The increased load bearing capacity is paralleled by decreased flexibility, making the lumbar region more prone to injury and accompanying LBP.
Viewed laterally, the spinal column presents several curves corresponding to the different vertebral regions. The cervical curve, which is the least marked, is convex forward from the atlas to T2. The thoracic curve is concave forward and reaches from T2 to T12. The lumbar curve which, like the cervical, is convex forward extends from T12 to L5. The spine additionally may present a slight lateral curve in the upper thoracic region. This laterally curve is generally convex to the right in right-handed persons, and convex to the left in left-handed persons.
Each vertebra consists of a ventral body which is solid, and a dorsal arch formed of two pedicles, two laminae, and seven lever-like processes, viz., four articular, two transverse, and one spinous. The transverse and spinous processes of the vertebrae serve as levers for the attachment of the muscles which articulate the spine. Together, the processes enclose a vertebral foramen which is occupied by the spinal cord, meninges, and their vessels. Opposing surfaces of adjacent bodies are bound together in a stack by intervertebral discs of fibrocartilage. In such an arrangement, the bodies of the vertebrae form a column-like structure for supporting the cranium and trunk, with the vertebral foramina forming an annular vertebral canal posterior of the bodies for receiving and protecting the spinal cord. Between adjoining arches, near their junctions with the bodies, are formed intervertebral foramina which transmit spinal nerves, smaller recurrent nerves, and blood and lymphatic vessels. The complete column of bodies and discs forms a strong but flexible central axis of the body. The column itself supports the full weight of the head and trunk, and, with the attached muscles, transmits even greater forces.
Although movement between adjacent vertebrae is limited to small ranges of motion, the summation of these ranges gives considerable degrees of bending freedom in flexion, extension, lateral flexion, rotation, and circumduction. The principal sites of movement between the vertebrae is found at the intervertebral discs. The elastic deformability of the discs facilitates tilting and torsion between the vertebral bodies, and additionally gives the column a degree of compressibility which allows the spines, with its curvatures, to better dampen stresses from the thrusts of the feet during walking, running, or jumping. Although the discs play a prominent role in spinal dynamics, regional variations in mobility also are affected by the disposition, properties, and geometries of intervertebral synovial joints and ligamentous complexes attached to the vertebrae.
Clinically, LBP generally is categorized as mechanical, which is centered in the lower lumbar region, sciatic, which radiates down the left in the distribution of the sciatic nerve, and stenosis, involving a compression of the caudal equina and an associated polyradicular pain pattern exacerbated with lumbar extension [2]. LBP often presents simply as a manifestation of strains and sprains of the spinal facet joints and soft tissues of the lower back area. Chilton, M. D., and Nisenfeld, F. G., "Nonoperative Treatment of Low Back Injuries in Athletes," Clinics in Sports Medicine, 12(3), pp. 547-55 (July 1993) [5]. Skeletal and discogenic causes, although somewhat less common, also are contributory and include spinal fractures, disorders of the vertebral discs such as herniations and spinal stenosis, and vertebral subluxations such as ithmic spondylolisthesis, spinal ostechondrosis, scoliosis, hyperlordosis, kyphosis, and other misalignments [1,2,5]. Vertebral subluxations, which result from the abnormal movement of subluxed vertebrae in response to applied physiologic loads, are known to particularly affect the spinal cord and its associated nerves through pressure or other interference or irritation mechanisms.
Heretofore, only 10% of 20% of patients with acute or chronic LBP could be given a definitive pathoanatomic diagnosis [5]. Indeed, it has been reported that only 2% of routine films taken in connection with the initial evaluation of patients complaining of LBP showed any significant radiographic findings [5]. More sophisticated and expensive imaging techniques, such as computed tomography (CT), magnetic resonance imaging (MRI), or myelography, therefore are often specified as part of the examination protocol, and heretofore have been believed required to make definitive diagnoses of herniated discs, spinal stenosis, and most tumors and infections [2]. Diagnoses made with even the more sophisticated imaging techniques such as MRI, however, do not always correlate with LBP [1]. Radiographs therefore continue to be frequently employed in the evaluation of patients with LBP [2]. In this regard, it has been suggested that imaging studies should not be used to make a diagnosis, for example, of herniated disc, spinal stenosis, or other pain syndromes, but rather to confirm diagnoses made on the basis of patient history and physical examination [2].
The pathology associated with a clinical diagnosis of LBP heretofore has been confirmed solely on the basis of the visual observation of anterior, posterior, or profile images of the spine. Objective assessment of subluxations, however, has proven difficult as resulting from deformations, pressure fractures, depressed fractures, and the like which require the measuring of individual differences. Accordingly, systems have been proposed for measuring spinal misalignments, deformations, and instabilities. For example, Benesh et al., U.S. Pat. No. 5,088,504, describe a device for measuring skeletal misalignments which involves determining the lateral weight distribution in a patient, which weight distribution may then be related to the skeletal distortion.
Brown et al., U.S. Pat. No. 4,899,761, describe an apparatus for measuring the instability of a motion segment of the spine. The device has a vertebrae distractor which includes a means for applying a constant rate of increasing force against adjacent vertebrae of the motion segment to separate the vertebrae, and a means for recording the changes in the resistance of the vertebrae to the separation. The data obtained then are compared to results obtained from motion segment units in unfixed cadaveric spines or to the subjective testing of the patient using a Kocher clamp.
Yamashita et al., European Patent Application 0 245 098, describe a method for judging the deformation of a vertebral body. The method involves measuring a central, front brim, and rear brim length from a digitized profile X-ray image of the vertebral body, and then determining ratios derived from such lengths to classify the body.
Although the above-described systems may be said to represent an advancement in the art of LBP assessment, such systems have yet to be universally accepted by practitioners as being either prohibitively costly or in lacking documented clinical benefits. Without an accepted methodology for localizing the source of LBP, the nonsurgical treatment thereof has focused on nonspecific modalities such as bed rest, administration of nonsteroidal, anti-inflammatory drugs, muscle relaxants, or narcotics, exercise, or chiropractic manipulation [2,5]. The failure of such generalized modalities, however, frequently leads to surgical treatments, but often without any clearly beneficial results [1].
In view of the uncertain prognosis of the generalized treatment modalities, there have been calls for improved methods of localizing the exact sources of LBP. Waddell, G., "A New Clinical Model for the Treatment of Low-Back Pain," Spine, 12(7), pp. 634-642 (1987) [6]. The preferred method would be part of a comprehensive and cost-effective management protocol for diagnosing and treating a patient presenting a LBP or the like, and would be adaptable for diagnosing subluxations of both intervertebral and appendicular articulations. It is apparent that such a method would be well-received by practitioners, and would represent an important improvement in physiatrics.